Synthesis of (S)-α-methyl-1,3-benzodioxole-5-ethanol and derivatives

ABSTRACT

A process for stereoselectively forming N-substituted dihydro-2,3 benzodiazepines which are useful as AMPA receptor antagonists. The process includes an opening reduction step which sets the stereochemistry of the intermediates and the final compounds to the desired enantiomer. The reduction step may be carried out by an enzymatic reduction.

This application is a division of application Ser. No. 09/260,449 filedon Mar. 2, 1999, now U.S. Pat. No. 5,986,114, which is a division ofapplication Ser. No. 08/843,307 filed on Apr. 14, 1997, now U.S. Pat.No. 5,919,954, which is a division of application Ser. No. 08/413,036filed on Mar. 28, 1995 (now U.S. Pat. No. 5,665,878), which is acontinuation-in-part of application Ser. No. 08/298,645 filed Aug. 31,1994 (now abandoned).

FIELD OF THE INVENTION

This invention relates to a novel process for synthesizing certaindihydro-2,3-benzodiazepine derivatives, and has special application to aprocess for producing these compounds in high enantiomeric purity andyields. It also relates to intermediates useful in the process.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,835,152 discloses that the compound1-(4-aminophenyl)-4-methyl-7,8-methylenedioxy-3,4-dihydro-5H-2,3-benzodiazepinepossesses central nervous system effects.

European patent application publication number EP-A1-0492485 discloses2,3-benzodiazepine derivatives and other dihydro-2,3-benzodiazepinederivatives also having central nervous system effects, in particularmuscle-relaxant and anticonvulsive activity. The compounds disclosed inEP-A1-0492485 are represented by the general formula. ##STR1## whereinR^(a) stands for a C₁₋₆ aliphatic acyl group, optionally substituted bya methoxy, cyano, carboxyl, amino, C₁₋₄ alkylamino, di(C₁₋₄ alkyl)amino,pyrrolidino, phthalimido or phenyl group, or by one or more halogen(s);or R^(a) is a benzoyl, cyclopropanecarbonyl, C₁₋₅ alkylcarbamoyl orphenylcarbamoyl group; or R^(a) is absent when a double bond existsbetween the N(3) and C(4) atoms;

R¹ means hydrogen; or R¹ is absent when a double bond exists between theN(3) and C(4) atoms;

R² means a C₁₋₃ alkyl group; or

R¹ and R² together stand for a methylene group and no double bond ispresent between the N(3) and C(4) atoms;

R³ means hydrogen or a C₁₋₄ aliphatic acyl group;

R⁴ represents hydrogen; a C₁₋₆ aliphatic acyl group optionallysubstituted by a methoxy, cyano, carboxyl, amino, C₁₋₄ alkylamino,di(C₁₋₄ alkyl)amino, pyrrolidino, phthalimido or phenyl group or by oneor more halogen(s); as well as a benzoyl, palmitoyl,cyclopropanecarbonyl, C₁₋₅ alkylcarbamoyl or phenylcarbamoyl group; andthe dotted lines represent valence bonds optionally being present, withthe proviso that no double bond exists between the N(3) and C(4) atomswhen both R³ and R⁴ stand for hydrogen.

International patent application publication number WO 92/11262 alsodiscloses certain dihydro-2,3-benzodiazepine derivates having centralnervous system effects, in particular antidepressive and/orantiparkinsonian action. The compounds may be represented by generalformula (A) above in which R¹ represents hydrogen, R² represents methyl,R^(a) represents hydrogen or a C₁₋₄ alkyl group optionally substitutedby a carboxyl or C₂₋₅ alkoxycarbonyl group, R³ represents hydrogen andR⁴ represents an aliphatic C₁₋₆ acyl, benzoyl or phenylacetyl group.

It is now known that the compounds disclosed in U.S. Pat. No. 4,853,152,EP-A1-0492485 and WO 92/11262 are potent antagonists of the AMPA(α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid) class ofreceptors in the mammalian central nervous system. They have potentiallywidespread applications as neuroprotective agents, particularly asanticonvulsants. Thus they may be useful in the treatment of epilepsy,cerebral ischemia, brain and spinal trauma, status seizures, Parkinson'sdisease and amyotrophic lateral sclerosis.

The dihydro-2,3-benzodiazepines disclosed in U.S. Pat. No. 4,835,152,EP-A1-0492485 and WO92/11262 possess a centre of asymmetry at position4. It is now known that the (R) enantiomers, for example,(R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine(also known as(R)-1-(4-aminophenyl)-3-acetyl-4-methyl-7,8-methylenedioxy-3,4-dihydro-5H-2,3-benzodiazepine),are more potent than the (S) enantiomers.

U.S. Pat. No. 4,835,152, EP-A1-0492485 and WO 92/11262 disclosesynthetic routes for preparing the dihydro-2,3-benzodiazepines. In theseroutes, the dihydro-2,3-benzodiazepine ring is formed by selectivelyreducing a corresponding 2,3-benzodiazepine compound using an inorganicor organic-inorganic and/or complex metal hydride, such as sodiumborohydride, followed if desired by separating optically active forms.

An elegant, stereoselective synthesis has now been found for preparingthe (R) enantiomers of the dihydro-2,3-benzodiazepines disclosed in U.S.Pat. No. 4,835,152, EP-A1-0492485, WO 92/11262 and of certain otherdihydro-2,3-benzodiazepines.

SUMMARY OF THE INVENTION

The present invention provides a process for the preparation of acompound having the general formula: ##STR2## wherein R is hydrogen orC₁ -C₁₀ alkyl; X is hydrogen, C₁ -C₁₀ alkyl, acyl, aryl, or carboxyl, ora substituted derivative thereof.

Novel and non-obvious intermediate compounds are formed during thisprocess which further allow the efficient synthesis of the titlecompounds. Some of the novel intermediates disclosed include hemiketaland hydrazone compounds: ##STR3## wherein Z represents a leaving atom orgroup such as a mesylate. Note that the R and X moieties retain the samemeanings throughout this specification.

Accordingly, it is an object of this invention to provide for a novelstereoselective process of forming dihydro-2,3 benzodiazepinederivatives.

Another object is to provide for a process of forming dihydro-2,3benzodiazepine derivatives which is efficient and economical, in thathigh yields and enantiomeric purity are obtained with fewer steps andless waste then previously disclosed.

Another object is to provide for novel intermediate compounds formedduring the synthesis of dihydro-2,3-benzodiazepines.

Other objects will become apparent upon a reading of the followingdescription.

DETAILED DESCRIPTION OF THE INVENTION

According to one aspect, the present invention provides a process forpreparing a compound having the general formula: ##STR4## wherein R ishydrogen or a C₁ -C₁₀ alkyl; and X is hydrogen, C₁ -C₁₀ alkyl, acyl,aryl, carboxyl or a substituted derivative thereof, or a protectinggroup, or a pharmaceutically acceptable salt thereof, said processcomprising cyclising a compound having the general formula ##STR5##wherein Z represents a leaving atom or group, to afford a compoundhaving the general formula I, whereafter, if desired, converting thecompound of formula I into another compound of formula I and/or forminga pharmaceutically acceptable salt.

It has been found that compounds of formula (I) can be prepared in highyield and high enantiomeric purity by the process according to theinvention.

As used herein, the term "C₁ -C₁₀ alkyl" represents a straight orbranched alkyl chain having from one to ten carbon atoms. Typicalstraight or branched C₁ -C₁₀ alkyl groups include methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl,isopentyl, n-hexyl, 2-methylpentyl, n-octyl, decyl and the like. Theterm "C₁ -C₁₀ alkyl" includes within it the terms "C₁ -C₄ alkyl" and "C₁-C₆ alkyl".

The term "aryl" represents an aromatic moiety, such as phenyl, thienyl,furyl, pyridyl, imidazolyl and polynuclear aromatic moieties, such asnaphthyl, phthalazinyl, quinolyl, fluorenyl, anthracyl andphenanthrenyl. The term "substituted aryl" represents an aryl groupsubstituted with one or more moieties chosen from the group consistingof halogen, hydroxy, cyano, nitro, C₁ -C₆ alkyl, C₁ -C₄ alkoxy, carboxy,acetyl, formyl, carboxymethyl, hydroxymethyl, amino, aminomethyl ortrifluoromethyl. Examples of substituted aryl groups include4-methylphenyl, 2-methylphenyl, 4-methoxyphenyl, 4-(i-propyl)phenyl,4-cyclopentylphenyl, 4-(t-butyl)phenyl, 4-acetylphenyl,4-trifluoromethylphenyl, 4-chlorophenyl, 2-bromophenyl, 3-iodophenyl,6-bromonaphthyl, 3,4-(methylenedioxy)phenyl, indanyl, 1,2,3,4tetrahydronaphthyl, and 1,2,4,4-tetramethyl-1,2,3,4-tetrahydronaphthyl.

The term "acyl" represents a hydrogen, a C₁ -C₆ alkyl group or aheteroatom (for example nitrogen, as in an amido group) attached to acarbonyl group. Typical acyl groups include formyl, acetyl, propionyl,butanyl, valeryl, hexanyl, carbamoyl, N-methylcarbamoyl and ureyl.

"Aryl", used in the formulae throughout the specification, represents anunsubstituted or substituted aryl group. Examples of values for Aryl arep-nitrophenyl, p-aminophenyl and p-(protected amino)phenyl such as p-(C₁-C₆ alkanoylamino)phenyl, for example p-acetylaminophenyl. Examples ofsuitable protecting groups may be found in McOmie, Protective Groups inOrganic Chemistry, Phenum Press, N.Y. 1973, and Greene and Wutz,Protecting Groups in Organic Synthesis, 2d. ed., John Wiley and Sons,N.Y., 1991.

R preferably represents a C₁ -C₃ alkyl group, for example methyl.

Examples of values for X are hydrogen, formyl, acetyl, propionyl andmethylcarbamoyl.

X preferably represents a C₁ -C₆ aliphatic acyl group, optionallysubstituted by a methoxy, cyano, carboxyl, amino, C₁ -C₄ alkylamino,di(C₁ -C₄ alkyl)amino, pyrrolidino, phthalimido or phenyl group, or byone or more halogens); or R is benzoyl, cyclopropanecarbonyl, C₁ -CSalkylcarbamoyl or a phenylcarbamoyl group.

The leaving atom or group represented by Z may be for example, a halogenatom or an organosulfonyloxy group, or may be generated in situ from thecorresponding compound of formula VIII in which Z represents hydroxy.

Particular values for Z when it represents a halogen atom are chlorineand bromine.

An organosulfonyloxy group represented by Z may be, for example, or C₁-C₄ alkanesulfonyloxy group, a trifluoromethanesulfonyloxy group or aphenylsulfonyloxy group in which the phenyl group is unsubstituted orsubstituted by one or two substituents selected independently from C₁-C₄ alkyl, C₁ -C₄ alkoxy, halogen, nitro and halo C₁ -C₄ alkyl.Particular values for Z are methanesulfonyloxy, phenylsulfonyloxy,p-toluenesulfonyloxy and p-nitrophenylsulfonyloxy.

It has been found that a much better yield is obtained by cyclising acompound of formula VIII in which Z is an organosulfonyloxy group ratherthan a compound of formula VIII in which Z is a halogen atom.

When Z represents a halogen atom or an organosulfonyloxy group, thecyclisation is preferably performed in the presence of a base selectedfrom alkali metal hydroxides, for example sodium or potassium hydroxide;alkali metal carbonates, for example sodium or potassium carbonates;alkali metal hydrides, for example sodium or potassium hydride; andalkali metal alkoxides, for example lithium, sodium or potassiumt-butoxide. The process is conveniently performed at a temperature inthe range of from -30 to 100° C., preferably from 0 to 50° C. Suitablesolvents include alkanols such as methanol or ethanol, and ethers suchas tetrahydrofuran.

A compound of formula VIII in which Z represents a leaving atom or groupmay be generated in situ, by reacting a for example compound of formulaVIII in which Z represents a hydroxyl group with a triarylphosphine inthe presence of an azidodicarboxylate ester. The reaction is analogousto the well known Mitsunobu reaction. Preferably the triarylphosphine istriphenylphosphine and the azodicarboxylate ester is diethylazodicarboxylate. The process is conveniently performed at a temperaturein the range of from -30 to 100° C., preferably from -10 to 50° C.Suitable solvents include ethers such as tetrahydrofuran. It will beappreciated that in this instance, the leaving group represented by Z isa triarylphosphonyloxy group such as triphenylphosphonyloxy.

The process according to the invention is of particular interest forpreparing compounds of formula (I) in which Aryl representsp-aminophenyl. Such compounds are preferably prepared by cyclising acompound of general formula VIII in which Aryl represents p-nitrophenyl,p-aminophenyl or p-(protected amino)phenyl, whereafter, if necessary,

(a) reducing a p-nitrophenyl group to afford a p-aminophenyl group, or

(b) deprotecting a p-(protected amino)phenyl group to afford ap-aminophenyl group.

According to a preferred aspect, the present invention provides aprocess for preparing a compound having the general formula I in which Ris methyl and X represents hydrogen, formyl, acetyl, propionyl orN-methylcarbamoyl or a pharmaceutically acceptable salt thereof, whichcomprises cyclising a compound having the general formula VIII in whichR is methyl, X is hydrogen, formyl, acetyl, propionyl, N-methylcarbamoylor a protecting group and Aryl is p-nitrophenyl, p-aminophenyl orp-(protected amino)phenyl, whereafter, if necessary;

(a) reducing a p-nitrophenyl group to afford a p-aminophenyl group;

(b) deprotecting a p-(protected amino)phenyl group to afford ap-aminophenyl group;

(c) removing a protecting group represented by X to afford a compound offormula I in which X is hydrogen; and/or

(d) acylating a compound of formula I in which X is hydrogen to afford acompound of formula I in which X is formyl, acetyl, propionyl orN-methylcarbamoyl; and, if desired, forming a pharmaceuticallyacceptable salt.

The nitro group in a p-nitrophenyl group may be reduced by a methodknown in the art, for example as described in EP-A1-492485. Thus it maybe reduced by reaction with hydrazine or hydrazine hydrate in thepresence of Raney nickel catalyst. Alternatively, it may be reduced byreaction with hydrogen, formic acid, ammonium formate, atrialkylammonium formate such as triethylammonium formate or an alkalimetal formate such as sodium formate or potassium formate, in thepresence of a Group VIII metal catalyst such as palladium on charcoal.Suitable solvents include alcohols such as methanol, ethanol orisopropanol, and ethers such as tetrahydrofuran, or acetone. Thereduction may conveniently be performed at a temperature in the range offrom -10 to 120° C.

The protecting group in a p-(protected amino)phenyl group may be removedin a conventional way. For example, a C₁₋₆ alkanoyl group may be removedby hydrolysis in the presence of a mineral acid, for examplehydrochloric acid.

Acylation of a compound of formula I in which X is hydrogen to afford acompound of formula I in which X is an acyl group, such as formyl,acetyl, propionyl or N-methylcarbomoyl, may be performed as described inEP-A1-492485.

The compounds of formula VIII in which Z represents a hydroxyl group orleaving atom or group are believed to be novel, and are provided as afurther aspect of the invention.

The compounds of general formula VIII may be prepared by a multistepprocess, starting from a methylenedioxyphenyl acetone derivative.

According to another aspect, therefore, the present invention provides aprocess for preparing a compound having the general formula: ##STR6##wherein R is hydrogen or C₁ -C₁₀ alkyl; and X is hydrogen, C₁ -C₁₀alkyl, acyl, aryl, carboxyl, or a substituted derivative thereof; saidprocess comprising the steps of:

a) providing a quantity of a compound having the formula: ##STR7## b)asymmetrically reducing the compound of formula II to yield a compoundhaving the formula: ##STR8## c) reacting the compound of formula IIIwith an arylaldehyde compound of formula Aryl.CHO to yield an isochromancompound having the formula: ##STR9## d) reacting the compound offormula IV with an oxidizing agent to yield a compound of the formula:##STR10## e) reacting the compound of formula V with a hydrazidederivative of formula H₂ NNHX to yield a compound of the formula:##STR11## f) reacting the compound of formula VI with a (i) sulfonylhalide reagent and a base, to form an intermediate sulfonate, followedby reacting the resultant sulfonate with a strong base; or (ii) bydirect Mitsunobu cyclization to yield the compound of formula I.

The novel process of this invention provides a synthesis of fewer steps,higher yields and stereoselectivity, and generates no heavy metal andvery little overall waste. The process includes an earlyenantioselective reduction step at which time the stereochemistry is setto the preferred isomer (in this case the (R) or (-) enantiomer for thefinal product).

The preferred process involves the early chiral reduction of a ketone toan alcohol. Substituents are added in a multi-step process to close thebenzo-fused pyran ring, before a hydrazine reagent is introduced to openthe ring and add the necessary nitrogen components. Finally, thesecondary ring is closed by addition of a strong base and the compoundis reduced to form the desired compound.

Most preferably, the chiral reduction step is the initial step in thesynthesis of the Formula (I) compounds from ketones. The chiralreduction may be effected by use of specific chemicals or, preferably,by using biological agents as disclosed below. Setting thestereochemistry early in the process is beneficial and allows for thelater steps to be carried out on relatively enantiomerically purematerial. This increases both throughput and enantiomeric purity.

The first step of the process involves a chiral reduction of thestarting material (preferably a 3,4-methylenedioxyphenyl acetonederivative) to produce a virtually enantiomerically pure alcoholderivative of 1,2-methylenedioxybenzene. Preferably, the enantiomerformed is the (S) or (+) stereoisomer of the alcohol. The most preferredstarting compound is 3,4-methylenedioxyphenyl acetone.

Alternatively, the initial step may involve the combination of a haloderivative of 1,2-methylenedioxybenzene with an enantiomericallyenriched epoxide. This also results in the production of a highlyenantiomerically enriched alcohol derivative of 1,2methylenedioxybenzene.

The material used to effect the chiral reduction initial step may beeither chemical or preferably biological. In the case of biologicalagents, the preferred agents are reducing enzymes, most preferred beingyeasts from the Zygosaccharomyces group. Other biological agents whichmay be used include: Pichia fermentans, Endomycopsis fibuligera,Nematospora coryli, Saccharomyces sp., Candida famata, Saccharomycespastorianus, Saccharomyces cerevisiae, Saccharomyces uvarum, Candidautilis, Saccharomyces globosus, Kluyveromyces dobzhansk, Kluyveromyceslactis, Candida albicans, bakers' yeast, Zygosaccharomyces rouxii,Lactobacillus acidophilus, Aureobasidium pullulans, Mortierellaisabellina, Rhizopus oryzae, Kloeckeva javanica, Hanseniasporavalbyensis, Octosporomyces octospori, Candida guilliermondi, Candidaparapsilosis, Candida tropicalis, Torulopsis taboadae, Torulopsisethanolitolerans, Torulopsis ptarmiganii, Torulopsis sonorensis,Trigonopsis variabilis, Torulopsis enokii, Torulopsis methanothermo, SAFinstant yeast, ashland yeast inact., Candida boidinii, Candida blankiiand Red Star yeast.

The desired intermediate formed in the initial step is an alcoholsubstituted congener of 1,2-methylenedioxybenzene, with the mostpreferred congener consisting of(S)-α-Methyl-1,3-benzodioxole-5-ethanol.

The desired intermediate compound formed in the initial step is thensubjected to a Pictet-Spengler reaction which provides for convergentfusion of the benzodiazepine carbon constituents. The preferred reagentof choice is p-nitrobenzaldehyde, although other reagents known to thoseskilled in the art, such as acetals, may be used. The preferredintermediates are dihydrobenzopyrans with the most preferred compoundbeing7,8-dihydro-7-methyl-5-(4-nitrophenyl)-5H-1,3-dioxolo-benzo[b]pyran.

The dihydrobenzopyran congener is then oxidized at the C5 position toyield a hemiketal derivative of the general formula: ##STR12##

The preferred oxidizing agents include potassium permanganate, DDQ(2,3-dichloro-5,6-cyano-1,4-benzoquinone) or others, with the mostpreferred agent being a sodium hydroxide, dimethyl sulfoxide and aircombination.

The C5-hemiketal is then reacted with a hydrazide derivative of formulaH₂ NNHX in the presence of acid in order to form the hydrazoneintermediate. In this step, the benzopyran ring is opened such that thehydrazone component becomes attached to the C5 carbon. The mostpreferred hydrazide is acetic hydrazide and is preferably reacted in arefluxing aromatic or protic solvent, with the preferred hydrazone beingof the general formula ##STR13## wherein R is CH₃, X is acetyl and Arylis p-nitrophenyl.

The hydrazone derivative is converted into the desired benzodiazepinering via intramolecular alkylation. This is accomplished by one ofseveral possible methods. The first method involves the addition of amixture of a sulfonyl halide reagent of formula YSO₂ X^(a) in whichX^(a) represents a halogen atom such as chlorine and which Y representsan organic group such as C₁ -C₄ alkyl, trifluoromethyl, or phenyl inwhich the phenyl group is unsubstituted or substituted by one or twosubstituents selected independently from C₁ -C₄ alkyl, C₁ -C₄ alkoxy,halogen, nitro and halo C₁ -C₄ alkyl (for example, methanesulfonylchloride) and a base, such as a tertiary amine (for example,triethylamine) to form a sulfonate intermediate of formula ##STR14##

The sulfonate is then converted to the 8,9-dihydro-7H-2,3-benzodiazepinecongener by addition of a strong base, most preferably an alkali metalhydroxide such as caustic soda, an alkali metal alkoxide such as sodiumor potassium tert-butoxide, an alkali metal carbonate such as potassiumcarbonate or an alkali metal hydride such as sodium hydride. optionally,the reaction may be performed in the presence of a phase transfercatalyst, such as tetrabutylammonium bromide.

Alternatively, the compound of formula VI may be converted into acompound of formula VIII in which z represents a halogen atom, forexample, a compound of formula VI may be reacted with imidazole,triphenylphosphine and bromine to afford a compound of formula VIII inwhich Z represents a bromine atom. The resultant compound for formulaVIII may then be cyclised following the same procedure as that used fora compound of formula VIII in which Z represents an organosulfonyloxygroup.

Surprisingly it has been found that the cyclisation of a compound offormula VIII in which Z represents an organosulfonyloxy group can beperformed in high yield, with remarkably little elimination. However,with a compound of formula VIII in which Z is a halogen atom, the yieldis substantially lower, due to competing elimination.

Accordingly, the use of a compound of formula VIII in which Z representsan organosulfonyloxy group (corresponding with a compound of formulaVII) is preferred.

Another method involves a Mitsunobu cyclization which is a one-stepprocess to yield the p-nitrophenyl benzodiazepine intermediate.

When a compound of formula I in which Aryl represents p-aminophenyl isdesired, and a compound of formula IV in which Aryl representsp-nitrophenyl has been prepared, the nitro group may be reduced at anystage in the process. Preferably it is reduced after process step e) or

The nitro group may be reduced by addition of hydrogen gas or a hydrogensource in the presence of a catalyst. The preferred hydrogen source ispotassium formate, or other formate salt (such as ammonium formate),with the preferred catalyst being a combination of palladium metal andactivated charcoal. The reduction step is well known to those skilled inthe art.

The preferred processes can be summarized by the following schemes toyield the most preferred product. ##STR15##

In scheme (I), the initial step of the process involves the addition ofbiological agents, most preferably Zygosaccharomyces rouxii, to reducethe ketone to the desired alcohol. A suitable quantity of an adsorbentresin such as AD-7, XAD-7, HP2MGL (cross-linked polymethacrylates fromRohm & Haas), HP20 (polystyrenic), or SP207 (brominated polystyrene fromMitsubishi) may be added to the reaction mixture to prevent death of theorganism and to adsorb the alcohol as it is formed.

Other similar resins may also be used. ##STR16##

In scheme (II), the initial step of the process involves reacting anaryl halide derivative, such as 4-bromo-1,2 (methylenedioxy) benzene,with an alkali metal hydrocarbon (sec-butyllithium is preferred) and anenantiomerically pure epoxide. Preferred is (S)-(-)-propylene oxide.Alternatively, an aryl halide may first be converted into a Grignardreagent by reaction with magnesium, then reacted with anenantiomerically pure epoxide in the presence of copper(I) iodide ascatalyst. In both scheme (I) and scheme (II), the objective is to setthe stereochemistry of the C8 atom of the benzodiazepine ring as earlyas possible. Both schemes have been observed to accomplish thisobjective and have formed enantiomerically enriched (ee) alcohols in the98% purity range.

The following examples are indicative of the process of this invention.

EXAMPLE 1 Synthesis of (S)-α-methyl-1,3 benzodioxole-5-ethanol

1 equiv. of 3,4-methylenedioxyphenyl acetone, 0.45 equiv. disodiumphosphate, 0.03 equiv. phosphoric acid, 12.5 volumes AD-7 resin and 5.8volumes of water were mixed together and stirred for 15-60 minutes at20-25° C. 2.27 equiv. of glucose were added and Z. rouxii ATCC₁₄₄₆₂ isadded in an amount of 1.5 grams wet cell paste per gram of ketone (thisis 0.375 grams/gram on a dry basis). This mixture was diluted with waterto 25 volumes and then gently stirred at 33-35° C. for 8-16 hours. Themixture was filtered on a 100 mesh (˜150 micron) stainless steel screen,and the resin which was retained by the screen was washed with 25volumes of water split into 4 separate portions. The product, which wasadsorbed to the resin, was then desorbed from the resin with 25 volumesof acetone. The acetone/product solution was then stripped to drynessunder vacuum to yield the title intermediate as a yellow, mediumviscosity oil. The in-situ yield was 97-100%, while the isolated yieldwas 85-90%. The potency was 80-95% and the EE is 100%.

EXAMPLE 2 Synthesis of (5RS,7S)-7,8dihydro-7-methyl-5-(4-nitrophenyl)-5H-1,3 dioxolo-[4,5-G][2]benzopyran

The above intermediate was dissolved in 4.64 volumes of toluene,filtered over hyflo, and washed with 1.55 volumes of toluene. 1.05equiv. p-nitro-benzaldehyde and 1.05 equiv. of conc. hydrochloric acidwere added, and the mixture was heated to 55-65° C. and stirred 1 hour.A solvent exchange was then conducted at 250 mmHg, replacing the toluenewith 12.4 volumes of 93% isopropanol/7% water/ The volume during thissolvent exchange varies from 11-14 volumes, and the final volume was ˜11volumes. The mixture was cooled to 0-10° C. and stirred 1 hour. Theneedle-like product crystals were filtered and washed 2 times with 1.85vol. isopropanol and dried under vacuum at 50-60° C. The in-situ yieldof the title compound was 95+% while the isolated yield was 87-93%. Thepotency was 99+% and the EE is 100%.

EXAMPLE 3 Alternative syntheses of (S)-α-methyl-1,3benzodioxole-5-ethanol

3.47 grams of 4-bromo-1,2(methylenedioxy)benzene were dissolved in 100ml of tetrahydrofuran at -78° C., 13.9 ml of 1.3M sec-butyllithium incyclohexane was then added to consume the aryl halide in less than 30minutes. 1.00 grams of (S)-(-)-propylene oxide in 2 ml THF was added bysyringe and the solution stirred for 45 minutes. The solution was thenwarmed to 23° C. for 16 hours. The reaction mixture was poured into 3Mammonium chloride solution and the product isolated by extraction withethyl acetate. The combined extracts were dried over magnesium sulfatefiltered through florisil and concentrated by rotary evaporation. Theresidual oil was purified by silica gel chromatography and eluted with a50:50 mixture of hexane and diethyl ether to yield 1.40 g (45%) of thesubtitled intermediate. Pchem: [α]₃₆₅ +117.2° (c 1.0, CHCl₃) TLC R_(f)=0.26 (50:50 hexane:ether); IR (CHCl₃) 3598, 3012, 2973, 2887, 1490,1249, 1041cm⁻¹ ; ¹³ C NMR (CDCl₃) d 147.75, 146.19, 132.26, 122.27,109.68, 108.30; mass spectrum, m/z (FD, M⁺) 180; Anal. Calcd. for C₁₀H₁₂ O₃ : C, 66.65; H, 6.71. Found: C, 66.42; H, 6.66.

EXAMPLE 4 Alternative Synthesis of(5RS,7S)-7,8-dihydro-7-methyl-5-(4-nitrophenyl)-5H-1,3-dioxolo-[4,5-G][2]benzopyran

244 grams of p-nitrobenzaldehyde was added to a solution of 300 grams ofthe intermediate formed in the biocatalyzed reduction step of Example 1in 4.45 L of toluene. 166.5 mL of concentrated hydrochloric acid wasadded dropwise over 15-20 min and the resulting mixture was heated to60° C. for 2.5 h. The mixture was cooled to room temperature andconcentrated by rotary evaporation. 3 L of ethanol was added and themixture was concentrated to a solid. A second 3 L portion of ethanol wasadded and the mixture was stirred for 1 h. The slurry was cooledovernight and the crystalline product was isolated by vacuum filtration.The filter cake was washed with ethanol and then dried in a vacuum ovenat 40-60° C. to yield 450 g (86%) of an off-white solid which wasdetermined to be an isomeric mixture of the above subtitled opticallyactive intermediate. P chem: [α]₃₆₅ +55° (c0.4, CHCl₃).

EXAMPLE 5 Synthesis of(5RS,7S)-7,8-dihydro-7-methyl-5-(4-nitrophenyl)-5H-1,3-dioxolo[4,5-G ][2]benzopyran-5-o1

350 grams of the isomeric intermediate from Example 4 was added to asolution of 731 mL of dimethylsulfoxide and 2923 mL ofdimethylformamide. The mixture was cooled to 8-12° C. and compressed airwas passed through the mixture. 117.5 mL of 50% aqueous sodium hydroxidewas added in one portion and the resulting mixture was stirred for 4.5h. The reaction mixture was added by cannula over 30-60 min to 8.25 L ofa stirred 1N hydrochloric acid solution at 10-15° C. The resultingprecipitate was filtered and washed with 3 L of water then air dried toa constant weight (384 g). The wet cake was carried into Example 6without further drying. P chem: Data recorded from a 3:1 isomericmixture. TLC R_(f) =0.19 (75:25 hexane:ethyl acetate); IR (CHCl₃) 3605,3590, 3015, 3000, 2960, 2910, 1608, 1522, 1484, 1352, 1240, 1042cm⁻¹ ; ¹H NMR (CDCl₃, 300 MHz) δ (major isomer) 8.16 (d, 2H, J=6.9 Hz), 7.73 (d,2H, J=6.9 Hz), 6.55 (s, 1H), 6.38 (s, 1H), 5.86 (s, 1H), 5.83 (s, 1H),4.38 (M, 1H), 2.70 (m, 2H), 1.39 (d, 3H, J=6.3 Hz); d (minor isomer)8.27 (d, 2H, J=8.9 Hz), 7.90 (d, 2H, J=8.6 Hz), 6.87 (s, 1H), 6.73 (s,1H), 6.03 (s, 1H), 6.02 (s, 1H), 3.95 (m, 1H), 2.7 (obscured, m, 2H),1.24 (d, 3H, J=6.1 Hz); mass spectrum, m/z (FD, M⁺) 329; Anal. Calcd.for C₁₇ H₁₅ NO₆ : C, 62.01; H, 4.59; N, 4.25. found C, 62.22, H, 4.79;N, 4.29.

EXAMPLE 6 Synthesis of (S)-aceticacid-[[6-(2-hydroxypropyl)-1,3-benzodioxol-5-yl](4-nitrophenyl)methylene]hydrazide

To 350 g of the wet cake from Example 5 in 2300 mL ethanol was added94.5 g of acetic hydrazide and 1 mL of concentrated hydrochloric acid.The resulting solution was heated to reflux for 2.5 h. The mixture wascooled to room temperature and concentrated to a yellow foam by rotaryevaporation. The concentrate was dissolved in 4.9 L of ethyl acetate andwashed with 1.5 L of saturated sodium bicarbonate then 1.5 L of brine.The organic phase was dried over sodium sulfate, filtered andconcentrated to give 373 g of a yellow foam (91%). The material wasidentified as a 1:1 inseparable mixture of isomers of the subtitledcompound (97% pure by HPLC). P chem: Data recorded from a 1:1 isomericmixture. mp 167.8-169.7° C.; TLC R_(f) =0.55 (ethyl acetate); IR (CHCl₃)3590, 3485, 3310, 1694, 1673, 1520, 1485, 1346cm⁻¹ ; ¹ H NMR (CDCl₃, 300MHz) δ 8.64, 8.50 (s, 1H, NH), 8.18 (d, 2H, Ar--H), 7.74, 7.71 (d, 2H,J=8, Ar--H), 6.99, 6.95 (s, 1H, Ar--H), 6.52, 6.50 (s, 1H, Ar--H), 6.06,6.05 (d, 2H, J=5, O₂ CH₂), 2.44 (s, 3H, CH₃), 3.87 (m, 1H, CH), 2.4-2.2(m, 2H, CH₂), 1.12, 1.10 (d, 3H, CH₃); ¹³ C NMR (CHCl₃, 75 MHz) d 209.94(C), 173.38, 173.43 (C), 149.38, 149.62 (C), 148.31, 148.58 (C), 147.90,148.18 (C), 147.54 (C), 142.5, 143.04 (C), 132.64 (C), 127.53, 127.61(CH), 123.75, 123.77 (CH), 122.86, 123.27 (C), 112.13 (CH), 110.55 (CH),108.03, 108.10 (CH), 108.03, 108.10 (CH), 101.83 (CH₂), 67.51, 68.08(CH), 42.37, 42.97 (CH₂), 23.48, 23.83 (CH₃), 23.48, 23.83 (CH₃), 20.47,20.55 (CH₃); [a]₅₈₉ +103.8° (c 1, CHCl₃); mass spectrum, m/z (FD, M⁺)385; Anal. Calcd. for C₁₉ H₁₉ N₃ O₆ : C, 59.22; H, 4.97; N, 10.90.Found: C, 58.99; H, 5.04; N, 10.68.

EXAMPLE 7 Synthesis of (S)-aceticacid[[6-[2-[(methylsufonyl)oxy]propyl]-1,3-benzodioxol-5-yl](4-nitrophenyl)methylene]hydrazide

340 grams of the Example 6 intermediate was dissolved in 2380 mL ofmethylene chloride. The solution was cooled to 0° to -10° C. and 187 mLof triethylamine was added. 78.2 mL of methanesulfonyl chloride was thenadded and the resulting mixture was stirred for 15-30 min. 510 mL ofwater was added. The isolated organic phase was washed with 460 mL of a1N hydrochloric acid solution and then 500 mL of brine. The methylenechoride solution was warmed to 35-45° C. and 4760 mL of hexane was addedover 90 min. The mixture was slowly cooled to room temperature and thencooled further to 0-5° C. The product was isolated by vacuum filtrationand dried in a vacuum oven at 40-50° C. to give 356.2 grams (87%) of anisomeric mixture of the subtitled compound as a yellow solid. P chem:Data Recorded from a 3:1 isomeric mixture. mp 150.5-152.5° C.; TLC R_(f)=0.80 and 0.73 (ethyl acetate); IR (CHCl₃) 1696, 1520, 1486, 1346, 1175,1041, 923 cm⁻¹ ; ¹ H NMR (CHCl₃, 300 MHz) 67 8.44 (S, 1H, NH), 8.20 (d,2H, J=8.8 Hz, Ar--H), 7.73 (d, 2H, J=8.6 Hz), 6.94 (d, 1H, J=2.7 Hz,Ar--H), 6.57 (d, 1H, 2.6 Hz, Ar--H) 6.08 (d, 2H, J=5.4 Hz), 4.77 (m, 1H,CH), 2.90 (s, 3H, SCH₃, major), 2.83 (s, 3H, SCH₃, minor), 2.66-2.57 (m,2H, CH₂), 1.30 (d, 3H, CH₃, minor), 1.26 (d, 3H, CH₃, major); massspectrum, m/z (FD, M⁺) 385; Anal. Calcd. for C₂₀ H₂₁ N3O₈ S: C, 51.83;H, 4.57; N, 9.07; S, 6.92. Found: C, 52.05; H, 4.53; N, 8.84; S, 6.96.

EXAMPLE 8 Synthesis of(R)-7-acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine

325 g of the Example 7 intermediate was dissolved in 3174 mL methanol.To the stirred solution was added 38.1 mL of 50% caustic soda solution.The resulting mixture was stirred for 4 h. 6348 mL of water was added tothe mixture and the contents were stirred for 3 h after which period theresulting precipitate was isolated by vacuum filtration. The materialwas dried in a vacuum oven at 45-55° C. to give 255 grams (97%) of thesubtitled compound which was 97.6% pure by HPLC area %. 221 grams of thedried material was further purified by reslurry in 1105 mL of ethanolwhich was heated to reflux. The resulting mixture was cooled to roomtemperature and the precipitate was isolated by vacuum filtration. Theisolate was dried in a vacuum oven at 45-55° C. to give 199 grams (90%)of the subtitled compound which was 100% pure by HPLC potency assay.

EXAMPLE 9 Synthesis of(R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5h][2,3]benzodiazepine

To 5 grams of the Example 8 intermediate in 50 mL of ethanol was added0.5 grams of 10% Pd/C wetted with water. The agitated slurry was treatedwith a solution of 4 grams of potassium formate in 4 mL of water. Theresulting mixture was stirred for 2.5 h and then filtered over Hyflo.The filtrate was concentrated to 10-20 mL by distillation and 22 mL ofwater was slowly added to the warm (78°) solution. The resulting mixturewas heated to 90° C. and then slowly cooled to room temperature. Theproduct was isolated by vacuum filtration and washed with 10-20 mL ofwater. The isolated solid was dried under vacuum at 50° C. to give 4.17grams (93%) of the subtitled final compound which was 100% pure by HPLCpotency assay. [α]₃₆₅ =-303.7 (c=1,methanol)

EXAMPLE 10 Synthesis of (5RS.7S)-7,8-dihydro-7-methyl-5-(4-nitrophenyl)-5H-1,3-dioxolo[4,5-G][2]benzopyran-5-ol

15 grams of the Example 4 intermediate (derived from the Z.rouxii-mediated ketone reduction) was dissolved in a solution of 75 mLof dimethylsulfoxide and 75 mL of dimethylformamide. The solution wascooled to 7-9° C. and then aereated with 40% oxygen in nitrogen. 7.62grams of 50% sodium hydroxide in water was added and the resultingmixture was stirred for 3-4 h. The reation was terminated and whilemaintaining the temperature ≦12° C., 120 mL of toluene was addedfollowed by a mixture of 45 mL of water and 10 mL hydrochloric acid. Thephases were separated and the organic layer was washed with 75 mL of a10% aqueous sodium thiosulfate solution. The organic layer containingthe subtitled intermediate was carried into the next step.

EXAMPLE 11 Synthesis of (S)-aceticacid-[[6-(2-hydroxypropyl)-1,3-benzodioxol-5-yl](4-nitrophenyl)methylenelhydrazide

To the toluene solution of the Example 10 intermediate was added 4.26grams acetic hydrazide and (0.01 volumes) hydrochloric acid. Theresulting mixture was heated to reflux for 3.5 h with removal of waterby a Dean-Stark trap. The reaction mixture was concentrated by vacuumdistillation to 1 volume. The concentrate was diluted with 105 mL ofmethylene chloride and washed with 50-55 mL each of saturated sodiumbicarbonate solution and brine. The organic solution was dried overmagnesium sulfate (0.25 wt. %) and filtered over a hyflo cake. Thefilter was rinsed with 1 volume of methylene chloride. The combinedorganic phase containing the subtitled intermediate was carried into thenext step.

EXAMPLE 12 Synthesis of (S)-aceticacid[[6-[2-[(methylsufonyl)oxy]propyl]-1,3-benzodioxol-5-yl](4-nitrophenyl)methylene]hydrazide

The methylene chloride solution containing the Example 11 intermediatewas cooled to 0 to -5° C. and 10 mL of triethylamine was added. 4.1 mLof methanesulfonyl chloride was added slowly to maintain a reactiontemperature ≦0° C. 1.5 volumes of water was added to the resultingsolution. The organic phase was separated and washed with 2.5 volumes of1N hydrochloric acid solution. The organic phase was isolated andconcentrated to half the original volume by atmospheric distillation.The product was precipitated by the dropwise addition of heptane (2:1volume heptane to organic concentrate) to the solution at 45° C. Thestirred mixture was cooled to 20-25° C. for 1 h, then cooled to 0 to -5°C. for 1-2 h. The precipitate was isolated by vacuum filtration andwashed with 3 volumes of 4:1 heptane: methylene chloride then dried in avacuum oven at 45-50° C. 17.43 grams of the subtitled intermediate (78%)was obtained as an optically active mixture of hydrazone isomers whichwas 97.7% pure by HPLC potency assay.

EXAMPLE 13 Synthesis of(R)-7-acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4,5-H][2,3]benzodiazepine

17.5 grams of the Example 12 intermediate was suspended in 175 mL ethylalcohol. To the stirred mixture was added 1.7 grams of powdered sodiumhydroxide. The resulting mixture was stirred for 1 h. 88 mL of water wasadded to the mixture and the contents were stirred for 1 h after whichperiod the resulting precipitate was isolated by vacuum filtration andwashed with 175 mL of water. The material was dried in a vacuum oven at70° C. to give 12.2 grams (86%) of the subtitled compound which was99.9% pure by HPLC potency assay.

EXAMPLE 14 Synthesis of(R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine

Using the product of Example 13, the title compound was prepared by anexperimental procedure the same as that described in Example 9.

EXAMPLE 15(R)-7-Acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine

1.05 grams (S)-Acetic acid[[6-[2-[hydroxy]propyl]-1,3-benzodioxol-5-yl](4-nitrophenyl)methylene]hydrazideand 0.78 grams triphenylphosphine in 70 mL tetrahydrofuran were cooledto 0° C. 0.57 grams diethyl azodicarboxylate in 5 mL tetrahydro-furanwas added dropwise over 15 min. The resulting mixture was stirred for 2h then warmed to room temperature for 2 h. The mixture was transferredto a separatory funnel and the solution was washed with 1N HCl, waterand brine. The organic phase was dried over magnesium sulfate, filteredand concentrated by rotary evaporation. The residue was eluted through asilica gel column (1:1 ethyl acetate:hexane). Fractions containing thedesired compound were concentrated to a yellow oil which solidified onstanding. The yellow crystalline material was slurried in 30 mL of CH₂Cl₂ and hexane (3:7) at 0° C. The precipitate was removed by filtrationand the filtrate was concentrated to a yellow foam. The residue wassuspended in 10 mL ethanol which was warmed to reflux then slowly cooledto room temperature. The precipitate was collected by filtration anddried in a vacuum oven at 60° C. to give 0.51 grams (50%) of thesubtitled product (100% ee) which was 98.3% pure by HPLC potency assay.

EXAMPLE 16-18

0.5 ml of frozen yeast suspension containing the microorganism of Table1 was added to 50 ml of a yeast-malt medium in a 250 ml flask. After 48hours of shaking, 1.0 ml of culture is added to an additional 50 ml ofmedium and shaken for 48 more hours. 3,4-methylenedioxyphenyl acetone isadded until the final concentration is 10 grams/liter along with 1 ml of10% glucose. The cultures are incubated and shaken for 24 hours, thenanalyzed by HPLC for presence of the chiral alcohol intermediate ofExample 1.

                  TABLE 1                                                         ______________________________________                                              Micro                     %                                               Ex. # organism Source Conversion % EE                                       ______________________________________                                        16    Candida famata                                                                             (C.f.)  A.T.C.C.                                                                             0.0     --                                       26418                                                                      17 Zygosaccharomyces (Z.r.) A.T.C.C. 77.8 99.5                                 rouxii  14462                                                                13 Mortierrela (M.i.) N.R.R.L. 1.7 94.3                                        isobellina  1557                                                           ______________________________________                                    

EXAMPLE 19 Synthesis of (S)-acetic acid[[6-[2-[methylsulfonyl)oxy]propyl-1,3-benzodioxol-5-yl](4-aminophenyl)methylene]hydrazide

To a suspension of the Example 7 intermediate (5.00 g) in 100 mLiso-propyl alcohol was added 10% Pd/C (1 g) followed by potassiumformate (3.7 g) dissolved in 8 mL water. A second portion of potassiumformate (3.7 g) was added after 1.5 h which was followed by addition of10% Pd/C (1 g). The starting material was consumed within 30 min. Themixture was filtered through a pad of diatomaceous earth andconcentrated. The residue was dissolved in methylene chloride and washedwith water and brine. The organic solution was dried over Na₂ SO₄,filtered and concentrated. The title compound (4.52 g) was isolated as alight yellow solid in 97% yield as a 1:1.3 isomeric mixture.

Data Recorded from a 1:1.3 isomeric mixture. TLC R_(f) =0.83(acetonitrile); IR (CHCl₃) 3010, 1670, 1628, 1332, 1174, 1041, 922 cm⁻¹; ¹ H NMR (CDCl₃, 300 MHz) d 8.18 (d, 2H, J=9.2), 7.39 (d, 2H, J=11.4),7.38 (d, 2H, J=10), 6.91 (s, 1H), 6.89 (s, 1H), 6.62 (d, 2H, J=8.5),6.61 (d, 2H, J=8.1), 6.57 (s, 1H), 6.56 (s, 1H), 6.06 (m, 4H), 4.71(sext., 2H, J=7), 3.9 (br s, 4H), 2.86 (s, 3H), 2.78 (s, 3H), 2.74-2.49(m, 4H), 1.29 (d, 3H, J=10.8), 1.25 (d, 3H, 10.8); mass spectrum, m/z(FD, M⁺) 433; UV max (ethanol) 326 nm (ε 20767), 231 (17587), 205(42765).

EXAMPLE 20 Synthesis of(R)-7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo[4,5-][2,3]benzodiazepine

To a solution of the Example 19 intermediate 0.51 g in 6 mL THF wasadded a single portion of lithium tert-butoxide (0.17 g). The solutionwas stirred at ambient temperature for 2 h, then warmed to 40-50° C. for4 h. The reaction was quenched by addition of 10 mL of 3M ammoniumchloride. The resulting mixture was diluted with 15 mL ether and washedwith 15 mL each of water and brine. The organic solution was dried overNa₂ SO₄, filtered and concentrated. The residue was dissolved in 5-10 mLof warm methylene chloride and the product precipitated by addition of10-20 mL of ether. The product was isolated by filtration, redissolvedin ethyl alcohol and concentrated. The title compound (0.23 g) wasisolated in 58% yield and 100% ee (HPLC chiral assay).

EXAMPLE 21 Methyl Semicarbazide

Into 200 mL of ethanol, cooled to 2.5° C. under a nitrogen blanket, wasdissolved 17 mL (350.4 mmol) of hydrazine monohydrate. To this cold,stirring solution was added dropwise over 2 h a solution of 10.3 mL(174.6 mmol) of methylisocyanate in 150 mL of toluene maintaining theinternal temperature <6° C. The clear, colorless solution was stirredfor 30 min. at 5-10° C. then evaporated and dried under vacuum to afford15.19 g of white solids. The solids were stirred in 40 mL of toluene andheated to reflux to provide a cloudy solution. After slowly cooling toroom temperature and stirring for 2 h, the suspension was filteredthrough coarse glass. The solids were washed with hexanes and driedunder vacuum at 50° C. to provide 13.39 g (86.4%) of the title compoundas a white crystalline solid, mp=116° C. MS (FD+)=89. IR:3362, 3303,1630, 1561 cm⁻¹. ¹ H NMR (DMSO): δ 2.57 (d, 3, J=4), 4.06 (br. s, 2),6.27 (br. s, 1), 6.94 (br. s, 1). ¹³ C NMR (DMSO): δ 160.87, 25.89.

EXAMPLE 22 Synthesis of(S)-2-[[6-(2-hydroxypropyl)-1,3-benzodioxol-5-yl](4-nitrophenyl)methylene]-N-methylhydrazinecarboxamide

In a nitrogen blanketed flask was dissolved 5.17 g (15.70 mmol) of theintermediate of Example 5 in 30 mL of ethanol. To this stirring solutionwas added 1.75 g (19.7 mmol) of methyl semicarbazide. The mixture washeated to reflux to dissolve the solids and then 5 drops of conc. HClwas added. Over 1 h at reflux, yellow solids precipitated out ofsolution. After 1 h, HPLC analysis indicated complete reaction, 38.2%and 55.4% of 2 product isomers and no remaining starting material. Theyellow slurry was slowly cooled to ambient temperature to stir for 1 hand then stirred for 30 min. in an ice water bath. The mixture wasfiltered through coarse glass. The solids were washed with ethanol anddried under vacuum at 50° C. to afford 5.08 g (81.2%) of the titlecompound as a yellow solid, mp=238° C. HPLC assay indicated two isomers,46.2% +53.1%. MS (FD+)=400. IR: 1692, 1345 cm⁻¹. ¹ H NMR (DMSO): δ 0.90(t, 3, J=6); 2.22 (m, 2); 2.72 (d, 3, J=5); 3.63 (m, 1); 4.42 (d, 1/2,J=6); 4.58 (d, 1/2, J=6); 6.10 (s,2); 6.69 (d, 1, J=8); 7.05 (d, 1,J=10); 7.32 (br. t, 1, J=4); 7.85 (d, 2, J=9); 8.18 (d, 2, J=9); 8.62(d, 1, J=8). ¹³ C NMR (DMSO) δ 24.27, 24.51, 27.18, 43.30, 43.73, 67.09,67.47, 102.45, 108.95, 109.19, 111.50, 111.54, 112.41, 112.45, 124.40,124.48, 124.69, 128.35, 133.47, 133.69, 144.55, 144.61, 144.68, 144.79,147.71, 147.76, 148.06, 149.39, 149.54, 156.11, 156.23. Anal. Calcd for:C₁₉ H₂₀ N₄ O₆ : C, 57.00; H, 5.03; N, 13.99; Found: C, 57.72; H, 5.01;N, 13.99.

EXAMPLE 23 Synthesis of(S)-N-methyl-2-[[6-[2-[-(methylsulfonyl)oxy]propyl]-1,3-benzodioxol-5-yl](4-nitrophenyl)methylene]hydrazinecarboxamide

In a nitrogen blanketed flask was slurried 2.00 g (5.00 mmol) of theExample 22 intermediate in 120 mL of dry THF. The mixture was heatedslightly to dissolve the solids then slowly cooled back to ambienttemperature without precipitation. To the yellow solution was added 1.1mL (7.89 mmol) of triethylamine. The solution was then cooled in an icewater/NaCl bath and 500 μL (6.34 mmol) of methanesulfonyl choride wasadded. After 30 min, HPLC showed complete reaction, 99.0% mesylate. Thereaction was quenched with 50 mL of water and transferred to aseparatory funnel with 100 mL of ethyl acetate. The organic layer waswashed with 1N HCl (50 mL) and brine (50 mL) then dried (Na₂ SO₄). Thesolvent was evaporated to afford 2.56 g of crude title compound as ayellow solid/foam. The crude title compound was dissolved in 12 mL ofCH₂ Cl₂ and the solution was heated to reflux. To the solution was added6 mL of hexanes dropwise inducing precipitation of yellow solids. Themixture was slowly cooled to ambient temperature while stirring. After 1h at ambient temperature, the mixture was filtered through coarse glassand the solids washed with hexanes. After drying at 50° C. and 30" Hg,the title compound was collected as 2.19 g (91.6%) of yellow crystals,mp=164° C. MS (FD)=478. IR: 1696, 1346 cm⁻¹. ¹ H NMR (DMSO): δ 1.12 &1.19 (d, 3, J=6); 2.52 (m, 2); 2.73 (d, 3, J=3); 2.98 & 3.03 (s, 3);4.76 & 4.84 (q, 1, J=6, 12); 6.13 (s, 2); 6.74 & 6.78 (s, 1); 7.16 &7.20 (s, 1); 7.33 (br t, 1, J=5); 7.86 (d, 2, J=9); 8.18 & 8.22 (d, 2,J=9); 8.76 (s, 1). ¹³ C NMR (DMSO) 67 21.35, 21.47, 27.09, 38.55, 79.50,79.91, 102.56, 109.34, 109.46, 111.34, 111.37, 111.72, 111.74, 124.37,124.42, 124.86, 128.26, 128.36, 130.01, 130.14, 143.74, 143.81, 144.22,144.32, 147.93, 147.98, 148.19, 148.25, 149.65, 155.97. Anal. Calcd for:C₂₀ H₂₂ N₄ O₈ S: C, 50.21; H, 4.63; N, 11.71: Found: C, 50.46; H, 4.71;N, 11.65.

EXAMPLE 24 Synthesis of(R)-7-N-methylcarbamoyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4.5-h][2,3]benzodiazepine

In a nitrogen blanketed flask was slurried 1.50 g of the Example 23intermediate in 40 mL of dry THF. The stirring, yellow mixture wascooled in an acetone/ice bath and 276 mg (3.45 mmol) of lithiumt-butoxide was added. After stirring for 1 h, HPLC analysis of thecloudy, orange/red mixture indicated 96.5% of the desired compound andonly 3.1% remaining starting material. After 90 min. the reaction wasquenched with 5 mL of saturated aqueous NH₄ Cl and the mixture wastransferred to a separatory funnel with 5 mL H₂ O and 60 mL of CH₂ Cl₂.The yellow organic layer was washed with 20 mL of 1N HCl, saturatedaqueous NaHCO₃, and brine then dried over Na₂ SO₄. The solvent wasremoved by evaporation to afford 1.29 g of crude title compound as ayellow solid/foam. MS (FD+)=382.2; Anal. Calcd for C₁₉ H₁₈ N₄ O₅ : C,59.68; H, 4.74; N, 14.65; Found: C, 60.00; H, 5.13; N, 13.75.

EXAMPLE 25 Synthesis of(R)-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7-N-methylcarbamoyl-7H-1,3-dioxolo[4.5-h][2,3]benzodiazepine

In a nitrogen blanketed flask was dissolved 902 mg (2.36 mmol) of theExample 24 intermediate in 9 mL of ethanol. To this solution was added90 mg of 10% Pd/C followed by a solution of 690 mg (8.20 mmol) ofpotassium formate in 0.7 mL of water. The formate solution was added viapipette over about 30 seconds and initiated an exotherm which reached53° C. after 2-3 min. After 15 min. HPLC analysis of an aliquot of thereaction mixture indicated only the desired product. The black reactionmixture was filtered through an ethanol wetted pad of celite overmicrofibre paper and the filter was washed with copious ethanol. Thefiltrate was evaporated to afford 953 mg of crude title compound aslight, yellow solids. After attempted recrystallization from aqueousethanol, the material was partitioned between water and ethyl acetate.The organic layer was washed with brine and dried over Na₂ SO₄. Thesolvent was evaporated and ethanol stripped from the product severaltimes to afford 647 mg (97%) of the title compound as a light tan toyellow solid, mp=142.4° C. Chiral HPLC assay determined 99.50% ee.

EXAMPLE 26 Synthesis of (S)-acetic acid[[6-(2-bromopropyl)-1,3-benzodioxol-5-yl](4-nitrophenyl)methylene]hydrazid

1.0 g (2.59 mmol) of the Example 6 intermediate, 0.265 g (3.89 mmol) ofimidazole, and 0.849 g (3.24 mmol) of triphenylphosphine were combinedin 10 mL of CH₂ Cl₂ at ambient temperature producing a golden yellowsolution which was cooled to 0° C. in an ice water bath. After coolingto 0° C., 0.414 g (2.59 mmol) of bromine was added. The resultingsolution was stirred for 90 min at 0° C. during which time it wasobserved to become slightly cloudy. The reaction was then quenched bythe addition of 6 mL of 1N HCl. The mixture was transferred to aseparatory funnel where it was washed twice with 20 mL of 1N HClfollowed by washing with 10 mL of a saturated brine solution. Theorganic solution was dried over Na₂ SO₄, and evaporated to areddish-brown, gummy solid. Chromatography on flash silica gel using 2:1ethyl acetate/hexanes afforded 0.71 g (78%) of the title compound. About5% of the styrene from elimination of the bromine was present as acontamiment. A mixture of hydrazone double bond isomers and amiderotomers was observed which complicated the ¹ H NMR spectrum. ¹ H NMR(CDCl₃) 1.39, and 1.44, and 1.58, and 1.65 (d, 3, J=6), 2.48 (s, 3),2.50-2.85 (m, 2), 3.85-4.15 (m, 1), 6.09 (s, 1), 6.11 (s, 1), 6.55 (s,1), 6.94(s, 1), 7.73 and 7.80 (d, 2, J=9 ), 8.19, and 8.20 (d, 2, J=9),8.37, and 8.45 (s, 1). MS(FD⁺)M⁺ =450 observed for C₁₉ H₁₈ N₃ O₅ Br.

EXAMPLE 27 Synthesis of7-acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4.5-H][2,3]-benzodiazepine

0.100 g (0.22 mmol) of the Example 26 intermediate was dissolved in 2 mLof dry THF and cooled to 0° C. in an ice water bath under a blanket ofnitrogen. 0.018 g (0.22 mmol) of lithium t-butoxide was then added. Themixture was stirred at 0° C. for 2 h during which time the progress ofthe reaction was monitored via HPLC. Since HPLC revealed thatapproximately 10% of product had formed and a substantial amount ofstarting material still remained, the flask was capped with a glassstopper and placed in a freezer at -35° C. for 3 days. After anadditional 8 h at room temperature, HPLC indicated 16% desired product.The reaction mixture was quenched with 1 mL of a 50% saturated aqueousNH₄ Cl solution and transferred to a separatory funnel with 10 mL of CH₂Cl₂. The mixture was washed twice with 10 mL of 1N HCl followed by 10 mLof a saturated brine solution. The organic solution was dried over Na₂SO₄, and evaporated to a yellow-brown gummy solid. Yield 0.05 grams. Thedesired product was formed in about 15% yield as judged by comparison ofthe ¹ H NMR spectrum and HPLC trace with those of authentic product. Themajor product resulted from elimination to the corresponding styrenederivative.

EXAMPLE 28 Alternative synthesis of(S)-α-methyl-1,3-benzodioxole-5-ethanol

To a suspension of magnesium turnings (17 g) in 50 mL tetrahydrofuranwas added dropwise a solution of 5-bromo-1,3-benzodioxole (93.6 g).After complete addition, the mixture was diluted with 250 mLtetrahydrofuran and the resulting mixture was stirred overnight. 13 mLof the solution (0.78 M) was transferred to a round bottom flaskcontaining copper(I) iodide (0.12 g). The resulting mixture was cooledto -50° C. and a solution of (s)-(-)-propylene oxide in 3 mLtetrahydrofuran was slowly added then stirred 10 min. The mixture wasdiluted with ether. The isolated organic phase was washed with water andbrine. The aqueous wash was extracted with ether (2×) and the combinedorganic solutions were dried over magnesium sulfate, filtered andconcentrated. The residue was purified by silica gel chromatography (50%ether in pentane) to give 1.66 g of the desired product (91%). ChiralHPLC analysis indicated that the optical purity of the material was98.3%.

EXAMPLE 29 Synthesis of(R)-7-acetyl-8,9-dihydro-8-methyl-5-(4-nitrophenyl)-7H-1,3-dioxolo[4,5-h][2,3]benzodiazepine

To a suspension of the Example 7 intermediate (1.53 g) in 60 mL toluenewas added 10 mL 1N sodium hydroxide and tetrabutylammonium bromide(0.053 g). The resulting mixture was stirred vigorously for 72 h. Themixture was washed with brine and the organic phase was dried overmagnesium sulfate, filtered and concentrated by rotary evaporation. Theresidue was dissolved in ethanol and concentrated to dryness to give1.05 of the title compound (86%). HPLC analysis indicated that <0.5% ofthe corresponding elimination product was generated.

What is claimed is:
 1. (S)-α-Methyl-1,3-benzodioxole-5-ethanol.
 2. Aprocess for preparing a compound of the general formula: ##STR17##wherein R is H or C₁ -C₁₀ alkyl; comprising the steps of: a) providing aquantity of a compound having the formula: ##STR18## b) asymmetricallyreducing the formula II compound by adding a microorganism thereto toform the compound of formula III.
 3. The process of claim 2 wherein step(b) further includes adding an adsorption resin to the formula IIcompound.
 4. The process of claim 2 wherein R is --CH₃.
 5. The processof claim 2 wherein said microorganism is Candida famata,Zygosaccharomyces rouxii, Mortierrela isobellina or Candidaguilliermondi.